Evaluation of cross-sectional root canal shape and presentation of new classification of its changes using cone-beam computed tomography scanning

The root canal system is considering the most important factor in endodontic treatment, due to the complexity of its anatomy and morphology. The aim of this study was to evaluate the cross-sectional root canal shape in three thirds (coronal, middle, apical) in different age groups using cone-beam computed tomography scanning (CBCT) and to present a new classification for root canal shape changes. This cross-sectional study included 300 CBCT scans for patient aged 20-70, and these scans were evaluated to study the morphology of the cross-sectional root canal shape in coronal, middle, and apical thirds among three age groups, namely the young (20-44), middle (45-59), and elderly (60-70). The root canal shape was classified as round, oval, long oval, and ribbon (with or without isthmus). The cross-sectional root canal shape was identified in two groups: canals with an unchanging (constant) shape and canals with changing shape. In turn, in canals with changing shape, the change could be identified in the region of the middle or apical thirds of the canal. The results showed that root canal shape changes in two cases: (1) the presence of one or more canals in the root (with or without isthmus between them), and (2) with age, as it was observed that the cross-sectional shape of the root canal becomes round in the apical third with age. A new classification of the changes of root canal shape in three thirds (coronal, middle, apical) was presented in this study. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.